Conventional technologies relating to a parking assist device having the kind of configuration described above includes one disclosed in Patent Document 1. In the device disclosed in Patent Document 1, when the shift lever is placed in the reverse position during parallel parking, steering initiation guide lines, vehicle width guide lines, and vehicle trajectory guide lines are superimposed on a camera image of the area to the rear of the vehicle and are displayed on a monitor. The vehicle is then driven in reverse, the vehicle is stopped when the steering initiation guide lines reach a target point, and the steering wheel is turned. A steering amount guide mark is moved by the turning of the steering wheel in this manner, and after the steering wheel is turned until the steering amount guide mark reaches the target point, the vehicle can be properly advanced into the parking space by driving the vehicle in reverse.
A technology relating to a parking assist device configured as described above is disclosed in Patent Document 2, which discloses performing a portion of the steering automatically to guide a vehicle into a parking position. In the technology disclosed in Patent Document 2, control is initiated with the vehicle body in a specific position with respect to a parking position, whereby the steering wheel is automatically turned by automatic steering control. As the driver moves the vehicle very slowly, the vehicle is moved into a traveling direction switching position. When the vehicle is in the traveling direction switching position, the front wheels are already steered appropriately for moving the vehicle into the parking position. The driver can then move the vehicle into the parking position by driving the vehicle in reverse.
[Patent Document 1] Japanese Laid-open Patent Application No. 2001-55099 (paragraph 0028, FIGS. 2, 3)
[Patent Document 2] Japanese Laid-open Patent Application No. 2000-335436 (paragraphs 0025 through 0027, FIGS. 1 through 3)
When the operations for introducing an automobile into a parking position are considered, the vehicle must be moved as precisely as possible along a path of introduction into the parking position. Reliable operation is desired particularly when parking is performed by a driver who is inexperienced in driving technique, or when the parking space is narrow. The aforementioned technologies disclosed in Patent Documents 1 and 2 are useful for such purposes.
However, even in a case in which the image from a camera is displayed on a monitor as described in Patent Document 1, the vehicle is stopped when the steering initiation guide line reaches the target point displayed on the monitor, and the steering wheel is turned, the vehicle sometimes cannot be properly introduced into the parking position when the vehicle is stopped in a position other than the optimal stopping position due to an incorrect stop timing. Similarly, the vehicle sometimes cannot be properly introduced into the parking position if the steering wheel is turned by an incorrect amount even when the vehicle is stopped in the correct stopping position. Particularly when the vehicle is introduced into a parking position on an inclined ground surface, the vehicle may move past the appropriate stopping position before stopping.
A technology such as the one disclosed in Patent Document 2, in which a portion of the operation for introducing the vehicle into the parking position is performed automatically, relieves the driver of the task of operating the vehicle. However, in the technology disclosed in Patent Document 2, the vehicle must be set in the correct position in an initial stage for initiating control.
From the perspective of the driver, the information necessary for parking must be acquired via the monitor the steering wheel must be properly operated, and the stopping position must be correct when the vehicle is introduced into the parking position as described in Patent Document 1. But, with the technology in which operations are automatically controlled, the vehicle must be set in the correct position in an initial stage, and this setting is difficult to perform.
An object of the present invention is to logically configure a device for correctly introducing a vehicle into a parking position even when driving operations for introducing the vehicle into the parking position are inadequate.